The invention concerns a process for making an elastomer assembly having an elastomer seal and at least one shaped elastomer portion.
Elastomer assemblies are known from a practical context in the area of vehicle construction, in which shaped elastomer portions and injection-molded portions are assembled to form an elastomer seal, for example a door frame seal. Previously, locally laminated elastomer profile portions have been produced on such elastomer seals, being applied thereto by hand. That procedure results in an elastomer assembly, the manufacture of which is comparatively complicated and expensive as the elastomer seal is generally of great length and is difficult to handle because of its flexibility. Furthermore, close tolerances are required for elastomer assemblies such that manufacturing procedures which were implemented previously by hand are complicated and expensive.
The object of the present invention is to facilitate and improve the production of such elastomer assemblies.
That object is attained by the present invention which provides for a process for making an elastomer assembly having an elastomer seal and at least one shaped elastomer portion, wherein in a step (a) a thermoplastic layer is applied to each shaped elastomer portion. In a step (b) the thermoplastic layer is converted into a molten state by heating. In a step (c) the elastomer seal and the at least one shaped elastomer portion are brought together along the thermoplastic layer, and, in a step (d) after the assembly operation of step (c), the thermoplastic layer is cooled down until the elastomer seal and the at least one shaped elastomer portion are fixedly connected together. The thermoplastic layer which is firstly converted into the molten state and then hardened again by cooling provides for a very firm and secure connection between the shaped elastomer portions and the elastomer seal. In addition this manufacturing procedure is effected in advantageously close production tolerances.
In step (a) above, a main elastomer body of each shaped elastomer portion and the thermoplastic layer can be co-extruded. In accordance with this feature, the subsequent application of an adhesive in an additional working step is avoided and the thermoplastic layer is applied very uniformly and in firmly bonded relationship to the shaped elastomer portion.
Furthermore, in step (a), the thermoplastic layer can be applied only to a first peripheral portion of each shaped elastomer portion. These features are sufficient to subsequently achieve an adequate connection to the elastomer seal.
As another feature, between steps (a) and (b) a textile cover can be applied by a laminating procedure to a second peripheral portion of each shaped elastomer portion. In accordance with this feature, the shaped elastomer portions can be produced in any desired manner by lamination.
Each shaped elastomer portion can be cut to length after step (a) and prior to step (b). Here, the shaped elastomer portions can be inexpensively produced by extrusion and subsequently cut to size.
The invention further provides a process as set forth above wherein between steps (a) and (b) at least a part of the length of the elastomer seal and the at least one shaped elastomer portion are introduced into a holding apparatus, the at least one shaped elastomer portion is lifted from the holding apparatus by a pick-and-place unit and positioned above an associated region of the elastomer seal, a heating apparatus is moved between the elastomer seal and the at least one shaped elastomer portion and heats the same until in step (b) the molten state of the thermoplastic layer is reached, the heating apparatus is then removed and in step (c) each shaped elastomer portion is pressed with its molten thermoplastic layer against the associated region of the elastomer seal by the pick-and-place unit, thereafter cooling in accordance with step (d) and movement of the pick-and-place unit away from the holding apparatus are effected, and then the elastomer assembly in the finished manufactured condition is removed from the holding apparatus. In accordance with this aspect of the invention, only the operation of introducing the elastomer seal and the shaped elastomer portions into the holding apparatus and the operation of removing the elastomer assembly in the finished manufactured condition from the holding apparatus are effected by hand. All other steps in the process are implemented by machine and with a correspondingly high level of precision. This has a highly advantageous effect on the dimensional accuracy and quality of the elastomer assembly. In principle only that part of the length of the elastomer seal which is to be subsequently produced with the at least one shaped elastomer portion is introduced into the holding apparatus. The remaining length of the elastomer seal is put down in a suitable fashion so that it does not interfere with the manufacturing procedure. It is possible in that way in one working operation to produce complete elastomer assemblies for a motor vehicle, for example the right-hand and left-hand door frames and a connecting portion along the windshield.
The invention further provides a process as set forth above wherein between steps (a) and (b) at least a part of the length of the elastomer seal and the at least one shaped elastomer portion is introduced into a holding apparatus in at least one handling station, the holding apparatus is thereafter moved into a processing station, in the processing station the at least one shaped elastomer portion is lifted from the holding apparatus by a pick-and-place unit and positioned above an associated region of the elastomer seal, in the processing station a heating apparatus is moved between the elastomer seal and the at least one shaped elastomer portion and heats the same until in step (b) the molten state of the thermoplastic layer is reached, then in the processing station the heating apparatus is removed and in step (c) each shaped elastomer portion is pressed with its molten thermoplastic layer against the associated region of the elastomer seal by the pick-and-place unit, thereafter cooling in accordance with step (d) and movement of the pick-and-place unit away from the holding apparatus are effected in the processing station, then the holding apparatus with the elastomer assembly in the finished manufactured condition is moved out of the processing station into the at least one handling station, and in said handling station the elastomer assembly is removed from the holding apparatus. The stations make it possible to increase efficiency and output in regard to making the elastomer assemblies.
Two holding apparatuses can be provided, and when one of the holding apparatuses is in the at least one handling station the other holding apparatus is arranged in the processing station. These features result in a further increase in efficiency and output.
The thermoplastic layer can comprise a modified polypropylene, and the thickness of the thermoplastic layer after step (a) can be between 0.1 mm and 0.6 mm, in particular about 0.3 mm. These features afford highly reliable connections between the shaped elastomer portions and the elastomer seal.
A further object of the invention is to provide an apparatus for making an elastomer seal and at least one shaped elastomer portion in the form of an elastomer assembly.
That object is attained by an apparatus for making an elastomer assembly having an elastomer seal and at least one shaped elastomer portion, the apparatus having a holding apparatus for receiving at least a part of the length of the elastomer seal and the at least one shaped elastomer portion, a thermoplastic layer facing towards the holding apparatus on each shaped elastomer portion, a pick-and-place unit with which the at least one shaped elastomer portion can be lifted from the holding apparatus and after a heating operation pressed against an associated region of the elastomer seal, and a heating apparatus temporarily movable between the holding apparatus and the pick-and-place unit for implementing the heating operation until the thermoplastic layer is in a molten state. The production procedure which is implemented substantially by machine affords elastomer assemblies of a high level of precision and operational reliability.
A cooling apparatus can be provided for cooling the manufactured elastomer assembly. This feature serves to accelerate hardening of the thermoplastic layer and thus the production of a strong bond between the shaped elastomer portions and the elastomer seal.
The cooling apparatus can be integrated into the pick-and-place unit. This affords a compact and effective cooling apparatus. Cooling already begins while the shaped elastomer portions are still being pressed by the pick-and-place unit against the elastomer seal.
The holding apparatus can have a respective cavity for the elastomer seal and the at least one shaped elastomer portion. In accordance with this feature, introduction of the elastomer seal and the shaped elastomer portions into the holding apparatus is facilitated.
The invention further provides for an apparatus as set forth above wherein there are provided two holding apparatuses, in at least one handling station the elastomer seal and the at least one shaped elastomer portion can be introduced into a first one of the holding apparatuses, the loaded first holding apparatus is movable into a processing station, the pick-and-place unit, the heating apparatus and the cooling apparatus are associated with the processing station, the first holding apparatus with the elastomer assembly in the finished manufactured condition is movable out of the processing station into the at least one handling station for removal of the elastomer assembly, and a second one of the holding apparatuses is arranged in the at least one handling station while the first holding apparatus is in the processing station. Furthermore, two handling stations can be associated with the processing station, the first holding apparatus can be reciprocal between a first one of the handling stations and the processing station, and the second holding apparatus can be reciprocal alternately with the first holding apparatus between a second one of the handling stations and the processing station. These features serve to speed up manufacture.
The holding apparatuses can be arranged on a carriage displaceable between the associated handling station and the processing station. Here, the reciprocating movement can be produced in a simple and precise manner.
In a further feature, the two holding apparatuses are rotatable about a horizontal axis arranged between them, and there is only one handling station. Here the apparatus is particularly compact and can easily be operate by just one operator.
In another feature, the holding apparatuses are arranged diametrically in relation to the horizontal axis and mounted on holding arms rotatably about their horizontal longitudinal axes relative to the holding arms, the holding arms are rotatable about the horizontal axis, and during the rotary movement of the holding arms an upper working side of each holding apparatus is always arranged upwardly. The features represent a structurally particularly advantageous configuration. The upper working side of each holding apparatus can easily always be held at the top for example by a suitable belt drive transmission.
As a further feature of the invention, the processing station is in a substantially closeable working space, and the handling station is arranged outside the working space. This facilitates temperature control, which is optimum for the procedure, in the working space or chamber, without the operator being stressed by virtue of elevated temperatures in the working space.
In another embodiment of the apparatus, a bulkhead is arranged between the holding apparatuses, the bulkhead is rotatable about the horizontal axis synchronously with the holding arms, and when the holding apparatuses are in the processing station and in the handling station the bulkhead seals off an opening in a wall of the working space. This ensures that the working space is adequately sealed off relative to the exterior during the working operation. In that way, there cannot be either unwanted heat losses out of the working space nor unwanted adverse effects due to draft into the working space.
In yet another embodiment of the apparatus the elastomer seal and the at least one shaped elastomer portion are arranged in mutually juxtaposed relationship in the holding apparatus, and besides a lifting movement the pick-and-place unit can also perform a lateral movement relative to the holding apparatus in order, prior to the at least one shaped elastomer portion being pressed against the elastomer seal, to orient the at least one shaped elastomer portion which has been lifted from the holding apparatus in aligned relationship with its associated region of the elastomer seal. This results in highly accurate alignment of the shaped elastomer portions with the elastomer seal before they are pressed together with the thermoplastic layer in the molten state.